Two Turkish soldiers have been killed and 31 people have been injured in a suicide attack carried out in a tractor filled with two tonnes of explosives by the Kurdistan Workers Party (PKK).

The tractor was driven at a military outpost in the Dogubeyazit district of eastern Agri province, bordering Iran, before it was detonated in the early hours of Sunday, the provincial governor’s office and the army said.

Survivors of the attack – which came amid heightened tensions after Turkey bombed Kurdish militants in northern Iraq – revealed the PKK militants also used rifles.

The Kurdish fighters drove a tractor filled with explosives at the military base in eastern Turkey at 3am

Four soldiers are said to be in a serious condition.

Meanwhile, another soldier was killed in Turkey’s southeastern province of Mardin when a unit on patrol was attacked by the PKK late on Saturday night, the army said. Seven soldiers were also wounded in the incident.

Armed attacks by PKK militants in southeastern Turkey have increased since mid-July, much more so since Turkey began a campaign of air strikes on PKK camps in northern Iraq on July 24.

In what prime minister Ahmet Davutoglu has called a ‘synchronised fight against terror’, Ankara has granted access of its bases to the U.S.-led coalition battling Islamic State.

However, so far the majority of Turkey’s air bombardment has been on PKK targets.

The military outpost was damaged in the bombing, which is the latest in a string of attacks which have increased after Turkey bombed Kurdish targets in northern Iraq

Turkish officials have said the strikes against the PKK are a response to increased violence.

The two sides have been in opposition for decades, with the PKK insurgency killing 40,000 since 1984.

Until now, a ceasefire, though fragile, had been holding since March 2013.

Sunday’s attacks have brought the number of security forces killed in attacks blamed on the PKK to at least 16 since July 20.

In an opinion piece published in Washington Post on July 31, Davutoglu said the operations would continue.

‘All terrorist organizations that target Turkey must know that their acts will not go unpunished and that we will respond to their acts with full resolve,’ he wrote.

‘This is not to say that the process of seeking a solution is over; on the contrary, I am determined to take it forward,’ he added.

Massoud Barzani, the president of Iraq’s Kurdistan region on Saturday condemned Turkey’s bombardment of a village there which he said had killed civilians, and called for a return to the peace process.

People have taken to the streets to protest against the bombings in Kurdish areas, calling for peace at rallies in Turkish capital Istanbul a week ago (pictured)

In his statement, he has also called on the PKK to distance the war from KRG territory.

‘The PKK forces must move the battlefields away from Kurdistan,’ he said.

Turkey’s foreign ministry said it was working with the Kurdistan Regional Government (KRG) to investigate claims of civilian casualties in the village of Zargala on Friday.

Western allies, including NATO and the United States, have supported Turkey’s actions but several have also urged it not to use excessive force or to let years of peace efforts with Kurdish militants collapse.